KR101369464B1 - Microphone - Google Patents

Abstract

The present invention relates to a MEMS microphone including: a printed circuit board; a MEMS chip which is combined with the printed circuit board and has a MEMS internal space; and a case which is combined with the printed circuit board, includes the MEMS chip, and forms an internal space which is separated from an external space, wherein the case is formed doubly into an internal case and an external case which have a middle sound path space between the internal and external cases. The printed circuit board has a board sound path which connects the middle sound path space with the MEMS internal space of the MEMS chip so that an external sound which come in through a sound hole enters the MEMS internal space of the MEMS chip through the middle sound path space.

Description

MEMS microphone {Microphone}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a MEMS microphone, and more particularly, to a microphone capable of sufficiently securing a back chamber space of a MEMS chip to improve acoustic characteristics.

The microphone is essentially used for a mobile communication terminal. Traditional condenser microphones consist of a diaphragm / backplate pair forming a capacitor C that changes in response to sound pressure, and a field effect transistor (JFET) for buffering the output signal.

In this conventional condenser microphone, a diaphragm, a spacer ring, an insulating ring, a back plate, and a conductive ring are sequentially inserted into a case, and finally, a printed circuit board on which circuit components are mounted is inserted, And bent to the substrate side to complete one assembly.

In recent years, semiconductor processing technology using micromachining has been applied as a technique for integrating micro devices in microphones. This technology, called MEMS (Micro Electro Mechanical System), can be used to fabricate ultra-small sensors, actuators and electromechanical structures in the order of micrometers by using micro-machining techniques, particularly those applied in semiconductor processing.

The MEMS microphone fabricated using such a micromachining technique is manufactured by miniaturizing, high-performance, multi-functional, and integrating traditional microphone parts such as a conventional diaphragm, a spacer ring, an insulating ring, a back plate, As a result, stability and reliability can be improved.

1 is a schematic cross-sectional view of one example of a conventional MEMS microphone 100 having a MEMS chip 120. As shown in FIG. The MEMS microphone 100 includes a printed circuit board 110, a MEMS chip 120 mounted on the printed circuit board 110, a special purpose semiconductor (ASIC) chip 130 and a sound hole 140 And a case 150 formed thereon.

In this configuration, the space indicated by reference numeral 126 is the MEMS internal space 126 formed inside the MEMS chip. In this type of MEMS microphone in which sound holes are formed in the case, the MEMS internal space 126 is a back chamber. The back chamber is a space for circulation of air generated during vibration of the diaphragm provided in the MEMS chip, and is a space for preventing negative resistance. That is, the space referred to as the back chamber means the space on the opposite side of the side from which the external sound is introduced with respect to the diaphragm. As the size of the back chamber increases, the sensitivity increases, and the SNR (single to noise ratio) value increases, which is desirable for the performance of the microphone.

2 shows a MEMS microphone 102 of a type in which a sound hole 140 is formed on a printed circuit board 110 instead of a case 150. [ No through holes are formed in the case 150. The external sound is introduced through the sound holes 140 formed in the printed circuit board 110. In this case, the back chamber is not the inner space of the MEMS chip, but the inner space 151 of the case serves as a back chamber.

2, since the back chamber is the internal space 151 of the case, sufficient space is ensured. However, in the case of the MEMS microphone 100 of FIG. 1, the back chamber is provided in the MEMS internal space 126 ), There is a disadvantage that it is not enough and is too small.

When the back chamber is too small as in the case of FIG. 1, there is a problem that the SNR value is small and the sensitivity is poor and the sound quality is deteriorated.

Patent Publication No. 2008-0005801

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a MEMS microphone which can sufficiently improve a sound quality by securing a space of a back chamber.

In addition, an object of the present invention is to provide a MEMS microphone, which is capable of sufficiently securing a space of a back chamber and has an excellent assembly property, and thus has a simple assembly process and excellent mass productivity.

MEMS microphone of the present invention, a printed circuit board: coupled to the printed circuit board, a MEMS chip having a MEMS inner space (MEMS chip); And a case coupled to the printed circuit board and including the MEMS chip to form an inner space that is distinct from an outer space. It is configured to include, wherein the case is configured to include an inner case and an outer case, the inner case, the lower end is coupled to the printed circuit board, to form the inner space, the outer case, It is provided so as to surround the inner case, and the lower end is coupled to the printed circuit board and coupled to form an intermediate acoustic passage space between the inner case, and the external sound into the intermediate acoustic passage space Perforated sound holes are formed to be introduced into the printed circuit board, and a substrate acoustic path is formed in the printed circuit board to communicate the intermediate sound passage space with the internal space of the MEMS chip, and the external sound introduced through the sound holes is It is characterized in that it is configured to enter the internal space of the MEMS chip through the intermediate acoustic passage space.

On the other hand, both the inner case and the outer case is preferably made of metal.

And, the lower side of the inner case and the outer case is preferably bonded to the printed circuit board by a conductive adhesive.

On the other hand, the inner case is fixed to the inside of the outer case, it is preferable to be fitted and fixed by an interference fit method.

In addition, the inner case is fixed to the inside of the outer case, the outer surface of the inner case is in surface contact with the inner surface of the outer case, a part of the outer surface of the inner case is the inner surface of the outer case It is preferably configured to be spaced apart from, so that the intermediate sound passage space is formed by the spaced portion.

The outer case may include four sidewalls and one upper wall, and the inner case may include four sidewalls and one upper wall, and the outer side of the upper wall may have a groove communicating with the sound hole. It is more preferable that a part of the four sidewalls is removed and provided with a partition wall so that a vertical passage is formed by the removed portion, and the intermediate sound passage space is formed by combining the groove portion and the vertical passage. .

On the other hand, the outer case is composed of four side walls and one top wall, the inner case is composed of four side walls and one upper wall, the upper wall is provided with a plurality of spacer protrusions protruding upwards An upper space is formed between an upper wall of the case and an upper wall of the lower case, and a portion of the four side walls is provided so that a vertical passage is formed by the removed portion having a partition wall. Preferably, the upper space and the vertical passage are combined to form the intermediate acoustic passage space.

According to the MEMS microphone of the present invention, since the internal communication portion includes an acoustic passage for communicating the internal space of the MEMS chip from the sound holes formed in the case, the back chamber can be increased to obtain an effect of improving the acoustic characteristics. .

In addition, according to the MEMS microphone of the present invention, since there is no additional assembly step for the configuration for securing the back chamber space, the effect of excellent mass productivity can be obtained. This can be achieved that the production cost does not increase.

1 is a schematic cross-sectional view of a conventional MEMS microphone,
2 is a schematic cross-sectional view of another conventional MEMS microphone,
3 is a schematic cross-sectional view of a MEMS microphone of one embodiment according to the present invention;
FIGS. 4 to 7 are views for explaining the structure of the MEMS microphone of FIG. 3,
8 is a schematic cross-sectional view of a MEMS microphone of another embodiment according to the present invention;
9 is a schematic cross-sectional view taken along the line VIII-VIII in FIG. 8.

Hereinafter, a MEMS microphone according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 7. FIG.

MEMS microphone 1 of the present embodiment is a device for converting sound waves, such as voice, sound, sound, etc. into electrical signals, mainly used in mobile phones, smart phones, small acoustic devices, etc., printed circuit board 10, MEMS chips It comprises 20 and a case.

In particular, the MEMS microphone 1 of the present invention relates to a type in which a sound hole into which sound is introduced from the outside is formed in a case, and is mainly used in a mobile communication terminal such as a mobile phone or a smartphone. However, the application is not limited to this, and it is possible to apply to all small-sized electronic apparatuses using a small-sized MEMS microphone.

The printed circuit board 10 is coupled to the open lower side of the case. The printed circuit board 10 forms a space distinguished from the external space by the printed circuit board 10 is coupled to the case. This space includes an interior space 34 and an intermediate sound passage space 44.

The printed circuit board 10 is formed with a substrate acoustic passage 15 for communicating the intermediate acoustic passage space 44 and the MEMS inner space 22 of the MEMS chip 20. The substrate acoustic passage 15 is formed inside the printed circuit board 10 in which a plurality of layers are stacked. The printed circuit board 10 is formed by stacking layers having through holes of a suitable shape, and the substrate acoustic passage 15 is formed by the union of the through holes formed in some layers. A printed circuit board having a substrate acoustic path may be manufactured by various conventional methods.

In this embodiment, the printed circuit board 10 includes a double-sided printed circuit board 11, an over-lay 12, and a PSR ink 13. .

Referring to FIG. 3, the substrate acoustic passage 15 includes an elongated low and long groove 15a formed in the double-sided printed circuit board 11 and two holes 15b formed in the coverlay member 12. 15c and holes 15d and 15e formed in the PSA ink member 13 communicate with each other.

On the other hand, the printed circuit board 10 is mounted with electrical components such as the MEMS chip 30 and the amplifier 25 directly or in the middle. The printed circuit board 10 is also called a die (DIE) printed circuit board because various electric components are mounted.

The MEMS chip 20, also called a MEMS transducer, is provided on the printed circuit board 10. Herein, the term 'equipped with' means that the MEMS chip 20 is directly mounted on the printed circuit board or indirectly mounted on the printed circuit board through another member. An empty space is provided inside the MEMS chip 30, which is called the MEMS inner space 22.

On the other hand, the component indicated by the reference numeral '25' is an amplifier. The amplifier 25 serves to amplify the electric signal received from the MEMS chip 20. The amplifier 25 is also called a special purpose semiconductor (ASIC) chip. Although not shown in detail, the MEMS chip 20 and the amplifier 25 are connected to each other by a conductive wire such as a gold bonding wire.

The case is coupled to the printed circuit board 10 to form an internal space 31. The internal space 31 includes the necessary electronic materials including the MEMS chip 20 therein, and is a space that is distinguished from the external space.

The case is configured to include an inner case 30 and an outer case 40.

The inner case 30 has a lower end coupled to the printed circuit board 10 to form an inner space 31. The outer case 40 is provided to surround the inner case 30 from the outside. The outer case 40 is coupled to the lower end of the printed circuit board 10 to form an intermediate acoustic passage space 44 between the inner case 30 and the inner case 30. On one side of the outer case 40, the through-hole formed in the sound hole 46 to be introduced into the external sound into the intermediate sound passage space 44 is formed.

In the present embodiment, both the inner case 30 and the outer case 40 are made of a metal material. Because of the metal material, it is possible to make a very thin thickness compared to the synthetic resin has the advantage of reducing the total volume. Lower surfaces of each lower end of the inner case 30 and the outer case 40 are coupled to the printed circuit board 10 by a conductive adhesive 50.

Unlike the conventional case, the case is made of a double case coupled separately. Since it is made of a metal double case and is bonded to the printed circuit board 10 by the conductive adhesive 50, the shielding and blocking effect from electromagnetic waves from the outside is compared with the case of the conventional single layer. The advantage is that it is significantly higher.

On the other hand, the lower end of each edge of the inner case 30 and the outer case 40 constituting the case is coupled to the printed circuit board 10, in addition to the conductive adhesive in a conventional method, such as conventional methods such as soldering or welding, etc. It can also be fixed by coupling.

In addition, in the present embodiment, the inner case 30 is fixed to the inside of the outer case 40, is fitted and fixed by an interference fit method. However, an intermediate sound passage space 44 is formed between the inner case 30 and the outer case 40.

That is, the inner case 30 is fitted into the outer case 40 to be fixed, and the outer surface of the inner case 30 is configured to be in surface contact with the inner surface of the outer case 40. However, the whole is not in surface contact, a part of the outer surface of the inner case 30 is configured to be spaced apart from the inner surface of the outer case 40, the intermediate sound passage space 44 is formed by the spaced portion It is configured to be.

More specifically, in the present embodiment, the outer case 40 includes four side walls 402 and one top wall 404. The inner case 30 is composed of four side walls 302 and one top wall 304.

The outer surface of the upper case 304 of the inner case 30 is formed with a groove portion 32 connected to the sound hole 46. In addition, in the inner case 30, a portion of the four side walls are provided with a partition 303 after being removed. The space formed by the partition wall 303 is provided to form a vertical passage. The intermediate acoustic passage 44 means a space in which the groove 32 and the vertical passage are combined.

That is, both the inner case 30 and the outer case 40 are in the shape of a hexahedron having an open lower side, and the inner case 30 is fitted and fixed to the inside of the outer case 40 by an interference fit method. Therefore, the two can be firmly coupled to each other by a process of simply inserting the inner case 30 into the outer case 30 without a separate fixing means. However, one edge portion of the inner case 30 is removed to form a vertical passage by the removed portion, and the groove portion 32 is formed by a portion recessed into a portion of the upper wall 304. The intermediate sound passage 44 is formed by the up-down passage and the groove 32.

Due to this configuration, the external sound introduced through the sound hole 46 passes through the intermediate acoustic passage 44 composed of the groove portion 32 and the vertical passage, and again through the substrate acoustic passage 14 to the MEMS chip 20. Enter the MEMS inner space (22). By forming such an acoustic path, the back chamber space can be made into the inner space 31 of the inner case 30 instead of the MEMS inner space 22, thereby improving the acoustic performance.

On the other hand, since the case is composed of the inner case 30 and the outer case 40, the inner space 22 is formed in more detail by the inner case 30 of the case, the inner case 30 and the outer An intermediate sound passage space 44 is formed between the cases 40. There is an expression 'case forms the internal space', but this expression is not an expression to exclude the intermediate acoustic passage space 44 formed by the case, and the internal space 22 and the intermediate acoustic passage space ( 44) is formed.

On the other hand, in the case of another embodiment the overall shape of the case can be variously modified. That is, the case may have a cylindrical shape, or may have a columnar shape in which the cross section in the horizontal direction is elliptical or polygonal. In this case, however, the case should be doubled and intermediate sound passage spaces formed between them.

The MEMS microphone 1 of this embodiment has the above-described structure and has the following actions and effects.

In this embodiment, the case is a double case consisting of an inner case 30 and an outer case 40, the intermediate acoustic passage space 44 is formed between them, the printed circuit board 10 in the substrate acoustic passage ( Since 15) is provided, the external sound introduced through the sound hole 46 is introduced into the MEMS inner space 22 of the MEMS chip 30 through the intermediate acoustic passage space 44 and the substrate acoustic passage 15. It is equipped with the structure that can be.

Therefore, in the conventional case in which sound holes are formed in the case, unlike the sound that is not satisfactory due to insufficient internal space of the MEMS, the size of the back chamber becomes the entire internal space 31 of the case. This has the advantage of being improved.

Since the size of the back chamber is one of the factors directly affecting the acoustic characteristics, in the case of this embodiment, the back chamber is remarkably enlarged and the acoustic characteristics are remarkably improved, compared with the type of similar conventional MEMS microphone.

In addition, the conventional MEMS chip is different from the type used in the MEMS microphone of the type of sound holes formed on the printed circuit board, and the type used in the MEMS microphone of the type of sound holes formed in the case. The advantage is that the same type used for the MEMS microphones formed on the circuit board can be used as it is, that is, there is no need to distinguish two types of MEMS chips according to the types of MEMS microphones. What is necessary is just to provide it.

In addition, since the case is formed of a double metal case, there is an advantage that the effect of blocking and shielding the influence of electromagnetic waves from the outside is excellent. In addition, when pre-assembled by inserting a double case, it is possible to use the conventional MEMS microphone manufacturing process as it is, there is an advantage that the entire assembly is possible without additional additional costs.

That is, as shown in FIG. 6, after preparing the printed circuit board 10, and preparing the case in which the inner case and the outer case 40 are coupled, the conductive adhesive 50 is shown in FIG. 7. , After coating along the shape of the lower end of each case, if the case is carried out the process, the entire assembly is completed. Its excellent productivity and productivity have advantages in terms of manufacturing cost.

On the other hand, in Fig. 8 a MEMS microphone 1 'of another embodiment according to the invention is illustrated as a schematic cross-sectional view. FIG. 9 is a view separately showing only the inner case 30 ′ of the configuration of the MEMS microphone of FIG. 8. On the other hand, as compared with the previous embodiment, in the case of the reference number, and performs the same function as the configuration using the same reference number, further description will be omitted.

The MEMS microphone 1 'of this embodiment is different from the previous embodiment in that there is no configuration of a' groove 'in the inner case 30'. The overall height of the inner case 30 'is lowered, and the spaced apart protrusions 32' are formed to secure the assemblability.

The external sound introduced into the sound hole 46 enters into the empty space above the upper wall 304 'secured by the spacer 32', passes through the vertical passage secured by the partition wall 303 ', and then returns to the substrate. The sound passage 15 enters the MEMS inner space 22. The intermediate sound passage space 44 'includes a space above the upper wall 304' and a vertical passage formed by the partition wall 303 '.

Meanwhile, in the above embodiments, the upper wall and the side wall are exemplified as angles, but the present invention is not limited thereto. The present invention can be applied to a shape where the boundary between the top wall and the side wall is gentle, such as the side dome shape.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

1 ... MEMS microphone
10 ... printed circuit board 15 ... board acoustic path
20 ... MEMS chip 22 ... MEMS inner space
30 ... inner case 40 ... outer case
44 ... medium acoustic path space 50 ... conductive adhesive

Claims (7)

Printed Circuit Boards:
A MEMS chip coupled to the printed circuit board and having a MEMS inner space; And
A case coupled to the printed circuit board, the case including the MEMS chip and forming an inner space different from the external space; , ≪ / RTI >
The case is configured to include an inner case and an outer case,
The inner case has a lower end coupled to the printed circuit board to form the inner space,
The outer case is provided to surround the inner case from the outside, and the lower end is coupled to the printed circuit board, and is coupled to form an intermediate acoustic passage space between the inner case and the intermediate sound. Perforated sound holes are formed to enter the external sound into the passage space,
The printed circuit board is provided with a substrate acoustic path for communicating the intermediate acoustic path space and the internal space of the MEMS chip,
Mess microphone (MEMS Microphone) characterized in that the external sound introduced through the sound hole is configured to enter the internal space of the MEMS chip through the intermediate sound passage space. The method of claim 1,
MEMS microphone, characterized in that both the inner case and the outer case is made of metal. 3. The method of claim 2,
The lower side of the inner case and the outer case, Memes microphone, characterized in that coupled to the printed circuit board by a conductive adhesive. The method of claim 1,
The inner case is fixed to the inside of the outer case, the MEMS microphone, characterized in that the fitting is fixed by the interference fit method. The method of claim 1,
The inner case is fixed to the inside of the outer case,
The outer surface of the inner case is in surface contact with the inner surface of the outer case, a portion of the outer surface of the inner case is configured to be spaced apart from the inner surface of the outer case, the intermediate acoustic passage by the spaced portion MEMS microphone, characterized in that configured to form a space. 6. The method of claim 5,
The outer case is composed of four side walls and one top wall,
The inner case is composed of four side walls and one upper wall, the outer surface of the upper wall is provided to form a groove communicating with the sound hole, a portion of the four side walls are provided with a partition after being removed It is provided so that the vertical passage is formed by the part,
MEMS microphone, characterized in that the intermediate sound passage space is formed by combining the groove and the vertical passage. 6. The method of claim 5,
The outer case is composed of four side walls and one top wall,
The inner case is composed of four side walls and one upper wall, and the upper wall is provided with a plurality of spaced-out protrusions protruding upward to form an upper space between the upper wall of the outer case and the upper wall of the inner case. And a part of the four side walls is provided to have a partition wall so that a vertical passage is formed by the removed part.
MEMS microphone, characterized in that the upper space and the vertical passage is combined to form the intermediate acoustic passage space.

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